Rolled roofing material is generally made of a glass fiber reinforced asphalt matrix with protective granules coated on one of the surfaces. The rolled roofing material is manufactured in long sheets which are then rolled up for ease of handling and transporting. The sheets of rolled roofing material are typically manufactured in 3 foot wide sheets and then rolled up by a roll-up machine to a diameter of about 9 inches. The rolls exit the roll-up machine on a conveyor and are typically oriented in a horizontal position. A plurality of rolls are then "palletized" or loaded onto a shipping pallet for storage and transportation. The rolls are placed vertically on the pallet such that they stand up on end. The plurality of rolls on the pallet are then often banded together for stability on the pallet.
In the past, the rolls of roofing material were palletized by workers manually lifting each roll from the conveyor and placing them on the pallet. However, the rolls of roofing material are relatively heavy and can weigh around 80 lbs. each. Therefore, the rolls of roofing material are cumbersome to manually handle. Manually lifting each roll is also labor intensive and time consuming. For these reasons, automated upender machines or "upenders" have been used to palletize the rolls of roofing material. Automated upenders typically include a platform or table for receiving a plurality of horizontally oriented rolls from the conveyor. For a conventionally sized pallet, four or five rolls in a linear arrangement can be loaded at a time onto the table. The rolls are loaded onto the table by automated actuator arms which push the rolls from the conveyor onto the table. After the rolls are loaded on the table, the table is pivoted to a first vertical position by a pneumatic or hydraulic cylinder. The rolls are supported by a bottom ledge extending from the table. A pair of movable side plates positioned adjacent the outermost rolls are moved by actuators so as sandwich the plurality of rolls. The side plates help prevent the rolls from moving or shifting when pivoted from the horizontal position to the first vertical position. Additional actuators then translationally move the table in a horizontal direction to a second vertical position above a pallet. The ledge is then retracted by actuators, thereby dropping the rolls onto the pallet. The table is then moved back to the conveyor to load another batch of rolls. The table is moved from the first vertical position to the second position by the same distance every time. Therefore, the pallet must be moved or indexed so that the next load of rolls is properly positioned on the pallet adjacent the previously load of rolls. To accomplish this task, the pallet is connected to an automated indexing machine which automatically re-positions the pallet after every load of rolls. Although the automated upender and the pallet indexing machine perform satisfactorily, the automated machines are very costly to manufacture and maintain. The automated upender and indexing machine can also occupy a large quantity of floor space.
It would therefore be desirable to have a system of palletizing rolls of roofing material onto a shipping pallet which is relatively inexpensive and easy to operate.